1. Field of the Invention
The invention relates to an apparatus for a connection point between a paper-insulated electrical high-voltage cable, which is impregnated with an insulating medium which can flow, and a plastic-insulated electrical high-voltage cable, in which an end termination, which is surrounded by a pressure-resistant partition isolator, is provided at the end of the paper-insulated high-voltage cable, and in which the connection point of the conductors of the two high-voltage cables is surrounded by electrical screening elements and a sleeve body (DE 42 09 831 C2).
2. Description of Related Art
An apparatus or a junction sleeve such as this is required to connect high-voltage cables, which have already been laid and are still in use, and whose paper insulation is impregnated with an insulating medium which can flow, to normal modern, plastic-insulated high-voltage cables. In known technology, oil or gas, for example nitrogen, are used as impregnation means for the first-mentioned high-voltage cables. These cables may be gas external-pressure cables, gas internal-pressure cables, low-pressure oil cables or high-pressure oil cables. In the following text, the word “paper cable” is used to represent all the possible embodiments. The plastic-insulated cable is referred to in the following text as a “plastic cable”, for the sake of simplicity.
At the ends which are intended to be connected to another high-voltage cable, the paper cable has a partition isolator, which is composed of epoxy resin by way of example, for pressure-tight closure. The partition isolator is shaped around the cable end, enclosing a circumferential annular gap, for the impregnation means to pass through. It has a relatively large external diameter, as an effective end closure. The connection point of a paper cable such as this to a plastic cable requires a correspondingly larger degree of complexity, because the external diameter of a plastic cable is considerably less than the external diameter of the partition isolator.
In the case of the known apparatus, which is referred to as a junction sleeve, according to the initially cited DE 42 09 831 C2, a winding composed of conductive strips is fitted around the connection point between the conductors of the paper cable and of the plastic cable. Sleeve insulation is located above the winding and is composed, for example, of self-welding strips based on ethylene-propylene rubber, which is wound on subject to tensile stress. The sleeve insulation has a constant external diameter and projects with correspondingly different thickness dimensions on the one hand to beyond the plastic cable and its exposed layers, and on the other hand to beyond the partition isolator of the paper cable. The entire connection point is surrounded by an aluminium foil as a diffusion barrier and by shrink sleeves as mechanical protection. In addition, this junction sleeve can be protected by a housing composed of glass-fibre-reinforced plastic. Overall, the production of this connection point or junction sleeve requires a considerable amount of effort.